Synthetic Biology and Microbial Fuel Cells: Towards Self-Sustaining Life Support Systems

NASA ARC and the J. Craig Venter Institute (JCVI) collaborated to investigate the development of advanced microbial fuels cells (MFCs) for biological wastewater treatment and electricity production (electrogenesis). Synthetic biology techniques and integrated hardware advances were investigated to increase system efficiency/robustness, with the intent of increasing power self-sufficiency and potential product formation from carbon dioxide. MFCs possess numerous advantages for space missions, including rapid processing, reduced biomass and effective removal of organics, nitrogen and phosphorus. Project efforts include developing space-based MFC concepts, integration analyses, increasing energy efficiency, and investigating novel bioelectrochemical system applications.

Innovative strategies are needed to overcome current limitations of wastewater treatment systems in space, while maximizing resource recovery (e.g., energy, water, CO2) and providing substantial cost savings. JCVI is developing MFC technologies that rapidly and efficiently treat high-organic wastewaters with simultaneous electricity generation. This approach employs fixed-film microbial communities as biocatalysts to efficiently oxidize organic compounds into electrons, protons and carbon dioxide. The electrons are biologically transferred to a conductive anode electrode and flow across the MFC circuit, generating a modest electric current. The reduction reactions occur at the MFC cathode electrode using a biotic or abiotic catalyst to reduce electrons, protons, and air to actually produce new (pure) water. This strategy accelerates treatment, decreases secondary sludge biomass, reduces waste gases from anaerobic digestion of solid material, controls unwanted fixed films by accelerated energy removal from biological components and does not necessitate solid and liquid waste separation. MFCs may also treat select “problem” compounds not captured by membrane-based technologies, thereby enabling a new class of water processing systems that significantly increase reliability and savings over current technologies.